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Intermittent short?

03-19-2010, 04:38 PM

I have a ceiling fan in my bedroom that I installed quite a few years ago. The light was switched (I put in a dimmer) The fan was controlled by pull chain. I stole the 1/2 switched outlet wire for the light instead. Years later, the breaker would trip every once and a while.

I checked connections and even swapped the breaker to rule that out. I then figured maybe the dimmer was the problem. I put in a regular switch and sure enough, went away. So yesterday I replaced the fan. Still with a regular switch. Breaker tripped while I was sleeping. Reset it and it's been fine all day. WTF?

I cant figure out a pattern and am wondering how to go about the diagnostic end since it's so intermittent!

any place where a nail could have drive into the wire? (saw a church where the roofers nailed through a conduit in a roof and the humidity would change the bright ness of the bulb),

is there any place where pets or uninvited guests, could bumping the wire, then check the boxes near that point? (had a friend who had a raccoon dig through the roof of his house and lived in the attic),

What else is on the circuit, it may not be the fan or the switch?

Is it at some time being over loaded by two motors starting at the same time?

look for loose wires or connections,

Push sticks/blocks Save Fingers
~~~~~~~~~~~~~~~~~~~
"The true measure of a man is how he treats someone who can do him absolutely no good."
attributed to Samuel Johnson
~~~~~~~~~~~~~~~~~~~
PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

Comment

Moisture is a possible problem since the connections are in the attic. I HAD a moisture problem due to a sagging fart fan exhaust that filled with water allowing moisture into the attic.
The other possibilites are hard to imagine cause it's conduit. Also, the fan stays on low speed all the time. The only thing that is on the curcuit is other lights (off most of the time) and some outlets with clocks and lamps.
I'll check into that. Thanks

Comment

your in Hvac so most likely you have an amp meter, take a amp meter and clamp on to the hot wire and see what the amp pull is and if it above what it calculates out to, (shut ever thing off on that line and check and then turn one thing on at a time) may find some thing,

Push sticks/blocks Save Fingers
~~~~~~~~~~~~~~~~~~~
"The true measure of a man is how he treats someone who can do him absolutely no good."
attributed to Samuel Johnson
~~~~~~~~~~~~~~~~~~~
PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

Comment

if the breaker is tripping and the breaker is not weak or bad, amps is what trips a breaker, so for some reason something has to be pulling amps, (yes it may be a short) but if a box is full of water some where, and shorting out via the water it would be pulling amps, if the wire is bear or scraped some thing has to making the wire move, (now that would not show up on a amp check), but for it to be intermediately tripping I would think there is some condition that is happening you have not seen or found, or not aware of, I do not know what else to suggest, at this point.

Push sticks/blocks Save Fingers
~~~~~~~~~~~~~~~~~~~
"The true measure of a man is how he treats someone who can do him absolutely no good."
attributed to Samuel Johnson
~~~~~~~~~~~~~~~~~~~
PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

Comment

I have a ceiling fan in my bedroom that I installed quite a few years ago. The light was switched (I put in a dimmer) The fan was controlled by pull chain. I stole the 1/2 switched outlet wire for the light instead. Years later, the breaker would trip every once and a while.

I checked connections and even swapped the breaker to rule that out. I then figured maybe the dimmer was the problem. I put in a regular switch and sure enough, went away. So yesterday I replaced the fan. Still with a regular switch. Breaker tripped while I was sleeping. Reset it and it's been fine all day. WTF?

I cant figure out a pattern and am wondering how to go about the diagnostic end since it's so intermittent!

Thanks in advance!
RJ

Check your bus bar in the breaker panel. Try moving the breaker to a different location in the panel.
I see a lot of electrical problems from bad bus bars especially with lighting and circuits with large loads.

I ASSUMED it wasnt over amping but I guess it certainly can't hurt. If we were talking bath fan with heat lamp or something, I could see it. I will try though. I'm on call today so I'll have time.

I think like Tod above. As you are saying "over amping it". Now were getting hot.

The symptom's do not point to the fan, breaker or the wiring. Simply the circuit is overloading it appears. Try to see what is running on that same circuit. Turn something off and see if it still trips.

Licensed Electrician

Comment

Shame, shame on me. Found the problem in the junction I made in the attic. Barely scuffing a wire on a bur I didn't clear on the conduit. Thankfully the breaker was doing it's job and it didn't spark a fire. Shame on me but.....it's fixed.
Just wanted to let you all know. Thanks guys!